Stefan Reinauer (stefan.reinauer@coreboot.org) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/1341
-gerrit
commit 1eb5629e24af2b52941848d57ae251565b5dc207 Author: Duncan Laurie dlaurie@chromium.org Date: Mon Jul 16 12:11:53 2012 -0700
ACPI: Add function to write _PPC using NVS
The existing NVS variable for PPCM will be used to select a dynamic max P-state.
By itself this does not change existing behavior because the NVS PPCM variable is initialized to zero.
PPCM can be tested by building and booting a modified BIOS that sets gnvs->ppcm to a value greater than 1 and checking from the OS that the P-state is limited to that value.
Change-Id: Ia7b3bbc6b84c1aa42349bb236abee5cc92486561 Signed-off-by: Duncan Laurie dlaurie@chromium.org --- src/arch/x86/boot/acpigen.c | 26 ++++++++++++++++++++++++++ src/arch/x86/include/arch/acpigen.h | 1 + src/cpu/intel/model_206ax/acpi.c | 2 +- 3 files changed, 28 insertions(+), 1 deletions(-)
diff --git a/src/arch/x86/boot/acpigen.c b/src/arch/x86/boot/acpigen.c index 71aa10c..47845a0 100644 --- a/src/arch/x86/boot/acpigen.c +++ b/src/arch/x86/boot/acpigen.c @@ -396,6 +396,32 @@ int acpigen_write_PPC(u8 nr) return len; }
+/* generates a func with max supported P states */ +int acpigen_write_PPC_NVS(void) +{ +/* + Method (_PPC, 0, NotSerialized) + { + Return (PPCM) + } +*/ + int len; + /* method op */ + acpigen_emit_byte(0x14); + len = acpigen_write_len_f(); + len += acpigen_emit_namestring("_PPC"); + /* no fnarg */ + acpigen_emit_byte(0x00); + /* return */ + acpigen_emit_byte(0xa4); + /* arg */ + len += acpigen_emit_namestring("PPCM"); + /* add all single bytes */ + len += 3; + acpigen_patch_len(len - 1); + return len; +} + int acpigen_write_TPC(const char *gnvs_tpc_limit) { /* diff --git a/src/arch/x86/include/arch/acpigen.h b/src/arch/x86/include/arch/acpigen.h index aebf508..5297aff 100644 --- a/src/arch/x86/include/arch/acpigen.h +++ b/src/arch/x86/include/arch/acpigen.h @@ -42,6 +42,7 @@ int acpigen_write_name_qword(const char *name, uint64_t val); int acpigen_write_name_byte(const char *name, uint8_t val); int acpigen_write_scope(const char *name); int acpigen_write_PPC(u8 nr); +int acpigen_write_PPC_NVS(void); int acpigen_write_empty_PCT(void); int acpigen_write_empty_PTC(void); int acpigen_write_TPC(const char *gnvs_tpc_limit); diff --git a/src/cpu/intel/model_206ax/acpi.c b/src/cpu/intel/model_206ax/acpi.c index 9784c47..f66df51 100644 --- a/src/cpu/intel/model_206ax/acpi.c +++ b/src/cpu/intel/model_206ax/acpi.c @@ -251,7 +251,7 @@ static int generate_P_state_entries(int core, int cores_per_package) len = acpigen_write_empty_PCT();
/* Write _PPC with no limit on supported P-state */ - len += acpigen_write_PPC(0); + len += acpigen_write_PPC_NVS();
/* Write PSD indicating configured coordination type */ len += acpigen_write_PSD_package(core, cores_per_package, coord_type);